1.
//更新前触发，不允许周日修改
create or replace trigger auth_secure before insert or update or DELETE
on tb_emp
begin
IF(to_char(sysdate,'DY')='星期日') THEN
RAISE_APPLICATION_ERROR(-20600,'不能在周末修改表tb_emp');
END IF;
END;
2.
//自增序列
CREATE OR REPLACE TRIGGER MY_TGR
BEFORE INSERT ON TAB_USER
FOR EACH ROW--对表的每一行触发器执行一次
DECLARE
NEXT_ID NUMBER;
BEGIN
SELECT MY_SEQ.NEXTVAL INTO NEXT_ID FROM DUAL;
:NEW.ID := NEXT_ID; --:NEW表示新插入的那条记录
END;
3.
//DML时，记录日志
--创建触发器
CREATE OR REPLACE TRIGGER TEST_TRIGGER
AFTER DELETE OR INSERT OR UPDATE ON TEST
DECLARE
V_TYPE TEST_LOG.L_TYPE%TYPE;
BEGIN
IF INSERTING THEN
--INSERT触发
V_TYPE := 'INSERT';
DBMS_OUTPUT.PUT_LINE('记录已经成功插入，并已记录到日志');
ELSIF UPDATING THEN
--UPDATE触发
V_TYPE := 'UPDATE';
DBMS_OUTPUT.PUT_LINE('记录已经成功更新，并已记录到日志');
ELSIF DELETING THEN
--DELETE触发
V_TYPE := 'DELETE';
DBMS_OUTPUT.PUT_LINE('记录已经成功删除，并已记录到日志');
END IF;
INSERT INTO TEST_LOG
VALUES
(USER, V_TYPE, TO_CHAR(SYSDATE, 'yyyy-mm-dd hh24:mi:ss')); --USER表示当前用户名
END;
4.
//创建触发器，它将映射emp表中每个部门的总人数和总工资
--创建映射表
CREATE TABLE dept_sal AS
SELECT deptno, COUNT(empno) total_emp, SUM(sal) total_sal
FROM scott.emp
GROUP BY deptno;
--创建触发器
CREATE OR REPLACE TRIGGER EMP_INFO
AFTER INSERT OR UPDATE OR DELETE ON scott.EMP
DECLARE
CURSOR CUR_EMP IS
SELECT DEPTNO, COUNT(EMPNO) AS TOTAL_EMP, SUM(SAL) AS TOTAL_SAL FROM scott.EMP GROUP BY DEPTNO;
BEGIN
DELETE DEPT_SAL; --触发时首先删除映射表信息
FOR V_EMP IN CUR_EMP LOOP
--DBMS_OUTPUT.PUT_LINE(v_emp.deptno || v_emp.total_emp || v_emp.total_sal);
--插入数据
INSERT INTO DEPT_SAL
VALUES
(V_EMP.DEPTNO, V_EMP.TOTAL_EMP, V_EMP.TOTAL_SAL);
END LOOP;
END;
--对emp表进行DML操作
INSERT INTO emp(empno,deptno,sal) VALUES('123','10',10000);
SELECT * FROM dept_sal;
DELETE EMP WHERE empno=123;
SELECT * FROM dept_sal;